[0001] This invention relates to antiperspirant compositions.
[0002] For inhibiting perspiration, the application to the skin of many different antiperspirant
active compounds has been described in the literature. However, those compounds most
widely used in commercial products at the present time are basic aluminium halides,
especially aluminium chlorhydrate, which has an Al/Cl molar ratio of about 2. These
active compounds are applied to the skin from a variety of applicator types including
aerosol sprays, pump sprays, squeeze packs, roll-ons and stick applicators. Thus aluminium
chlorhydrate, for example, is employed as the active ingredient of various liquid,
cream, stick or dry powder antiperspirant compositions. However, in spite of the popularity
of aluminium chlorhydrate the presently available products are capable of producing
only limited reduction in perspiration.
[0003] In our German patent application P 27 00 711.0, incorporated herein by reference,
and referred to hereinafter as the first application, there is described an improved
antiperspirant active compound which comprises a basic aluminium chloride, bromide,
iodide and nitrate having an aluminium to chloride, bromide, iodide or nitrate molar
ratio of from 6.5 to 1.3:1, and which compound forms in water a solution containing
polymeric species of a size greater than 100 Angstroms within which species there
is contained at least 2% by weight of the total aluminium. Since in aqueous solutions
of the basic aluminium compounds the halide or nitrate is in ionic form the polymeric
species present are hydroxyaluminium species. The antiperspirant active compound may
be employed in the form of an aqueous solution or the solution may be spray dried
to give a hydrated compound of the empirical formula:
Al
2(OH)
6-aX
a.nH
2O
where X is 01, Br, I or N0
3, a is from about 0.3 to 1.5 and n is from about 0.3 to 8.
[0004] As described in said first application, these special forms of basic aluminium compounds
which in aqueous solution contain polymeric species having a size greater than 100
Angstroms within which at least 2% by weight of the total aluminium is contained,
may be prepared by heating aqueous solutions of basic aluminium compounds at elevated
temperature. The production of the desired species depends on the appropriate choice
of the reaction conditions which are interrelated. It is preferred to use temperatures
of from 80°C to 140°C
o The period of heating may be shorter as higher temperatures are used, ranging for
example from 0.5 hour to 30 days. Of importance is the concentration of the basic
aluminium compound starting material. The rate of production of the higher polymeric
species of the basic aluminium compound decreases as the concentration of the solution
is increased and at the above temperatures the concentration should be no more than
about 35% by weight.
[0005] In our German patent application P 28 18 321.3
and referred to herein as the second application, we have described an improvement
in aqueous solutions of the antiperspirant agents bf the first application. This improvement
consisted in the inclusion in the solution of a neutral amino acid, by which was meant
an amino acid containing an equal number of unneutralised amino and acidic groups.
By the inclusion of the amino acid reduction of solution viscosity is effected and
gelling inhibited, particularly of aqueous alcoholic solutions.
[0006] We have now found that these advantages can also be obtained through the inclusion
of urea in the solution.
[0007] According to the present invention therefore there is provided an antiperspirant
composition comprising an aqueous solution of a basic aluminium chloride, bromide,
iodide or nitrate having an aluminium to chloride, bromide, iodide or nitrate molar
ratio of from 6.5 to 1.3:1 which solution contains polymeric hydroxyaluminium species
of a size greater than 100 Angstroms within which there is contained from 2 to 80%
by weight of the total aluminium, and which solution also contains urea as a gelation
inhibitor.
[0008] The amount of the urea included in the aqueous solution, which may be an aqueous
alcoholic solution, of the basic aluminium compound is preferably such that the aluminium
to urea molar ratio is from 20:1 to 1:10. The amount of urea necessary to substantially
inhibit gelation will depend on the concentration of the basic aluminium compound
in the solution and on the amount of any alcohol present, the higher concentrations
of the basic aluminium compound and/or alcohol requiring the use of greater amounts
Df urea.
[0009] The basic aluminium compound preferably has an aluminium to chloride, bromide, iodide
or nitrate molar ratio of from 4 to 1.3:1, more particularly to 2.5 to 1.6:1.
[0010] The weight of the aluminium in the species having an effective diameter above 100
Angstroms is preferably from 5 to 60% of the total aluminium.
[0011] The aqueous solution of the active antiperspirant agent comprising the higher polymeric
species as defined, may, if desired, be evaporated to concentrate the solution or
it may be dried to give a solid hydrated material. As with ordinary aluminium chlorhydrate,
for example, drying conditions which lead to both the loss of water of condensation
and hydrochloric acid should be avoided as these may lead to irreversible degradation
of the basic aluminium compound. Any suitable method of drying may be used, spray
drying being a particularly useful method. The spray drying method described in US
Patent No. 3,887,692 may be employed. The solid material may be ground or milled as
required. Drying should be effected in such manner as to give a product having a water
content consistent with the following empirical formula:
Al
2(OH)
6-aX
a.nH
2O.(Urea)
m
where X is Cl, Br, I or N0
3, a is from about 0.31 to 1.5, n is from about 0.3 to 8, preferably 0.3 to 4, and
m indicates the amount of urea and is preferably about 0.1 to 20.
[0012] The compositions of the invention may be made by dissolving the urea in the solution
of the basic aluminium compound containing the polymeric species greater than 100
Angstroms prepared as described in the first application referred to above. Alternatively
the urea may be included in a solution made up from the powder obtained by drying
the solution prepared according to the said first application referred to above. A
further method is by dissolving the solid, urea-containing antiperspirant compounds
described in the preceding paragraph in water or a water- alcohol mixture.
[0013] The compositions of the invention comprising the basic aluminium compound and urea
may contain up to 75% by weight of a C
l-C
3 aliphatic alcohol. These aqueous alcoholic compositions preferably contain ethanol,
propanol, isopropanol or a mixture thereof as the alcohol. The basic aluminium compound
is desirably present in the aqueous or aqueous alcoholic solution in a concentration
within the range 1 to 25% by weight.
[0014] The antiperspirant composition of the invention may be applied to the skin in various
known ways. Thus the aqueous solution may be applied from a pump spray applicator
or from a roll-ball applicator. Conventional ingredients may be included in such compositions,
for example, perfume (usually from 0.1 to 2% by weight) or thickener (usually 0.1
to 5% by weight).
[0015] The following Examples illustrate the invention. Percentages are by weight.
Examples 1 and 2
[0016] A spray dried antiperspirant powder was made according to Example 2 of the first
application referred to above. Aqueous alcoholic solutions of this material and urea
were made up. They were prepared by mixing ethanol with the powder to form a slurry
to which was added the urea followed by the water. The amounts of the ingredients
used are indicated below.

Example 3
[0017] An aqueous solution of the antiperspirant material used in Examples 1 and 2 was made
by dissolving 15 parts of urea in 65 parts of water after which 20 parts of the antiperspirant
powder were stirred in. The urea prevented gelation of the solution.
Example 4
[0018] 120 g of urea were dissolved in 2 kg of the treated solution made according to Example
9 of the first application referred to above. The solution was dried in a cocurrent
spray drier using inlet and outlet temperatures of 250°C and 95
0C, respectively. The resulting powder had the following empirical formula:
Al
2(OH)
5.1Cl
0.9(H
2O)
0.4(urea)
1.9
[0019] A further sample of the treated solution to which no urea had been added was similarly
spray dried to give a powder having the empirical formula:
Al
2(OH)
5.1Cl
0.9(H
2O)
1.5
[0020] Solutions of these powders in aqueous alcohol having the same aluminium concentration
were prepared from the following ingredients:

[0021] The solutions were prepared by mixing the ethanol with the respective powder to form
a slurry to which was added the water. Stirring was maintained throughout the process.
[0022] The solution obtained using the powder containing urea showed no sign of gel formation
after 1 week whereas the other solution had gelled.
1. An antiperspirant composition comprising an aqueous solution of a basic aluminium
chloride, bromide, iodide or nitrate having an aluminium to chloride, bromide, iodide
or nitrate molar ratio of from 6.5 to 1.3:1 which solution contains polymeric hydroxyaluminium
species of a size greater than 100 Angstroms within which there is contained from
2 to 80% by weight of the total aluminium, and which solution also contains urea as
a gelation inhibitor.
2. An antiperspirant composition as claimed in claim 1 wherein the amount of urea
is such that the aluminium to urea molar ratio is from 20:1 to 1:10.
3. An antiperspirant composition as claimed in claim 1 or claim 2 wherein the solution
is an aqueous alcoholic solution comprising a Cl-C3 aliphatic alcohol in an amount up to 75% by weight.
4. An antiperspirant composition as claimed in any of the preceding claims comprising
from 1 to 25% by weight of the basic aluminium compound.
5. A solid antiperspirant composition produced by drying the aqueous composition claimed
in claim 1 or claim 2 and having the empirical formula:

where X is Cl, Br, I or N0
3, a is from 0.31 to 1.5, n is from 0.3 to 8, and m indicates the amount of urea.